* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: PingFang SC;
}

a {
  text-decoration: none;
  color: #000;
}

ul {
  list-style: none;
}

.app {
  display: flex;
  column-gap: 20px;
  width: 980px;
  margin: 100px auto;
}

.app-left {
  width: 200px;
}

.app-left ul {
  display: flex;
  flex-direction: column;
  row-gap: 3px;
}

.app-left li {
  cursor: pointer;
  border-radius: 4px;
}

.app-left a {
  display: inline-block;
  padding: 10px 30px;
  width: 100%;
  height: 100%;
  border: 1px solid #999;
}

.app-left a.active {
  background-color: #01a1ff;
  color: #fff;
}

.app-right {
  flex: 1;
  min-height: 600px;
  padding: 20px;
  border: 1px solid #999;
  border-radius: 6px;
}
